1. Inventive Field
The embodiments disclosed herein relates to electrohydraulically trimming, flanging, and hemming blanks such as, but not limited to, stamped automotive body panels.
2. Background Art
The trimming of sheet metal parts in industry is well known. Modern production utilizes a wide variety of materials for interior panels, exterior panels, and structural parts such as Deep Drawing Quality Steels, Drawing Quality Steels, Bakehardenable Steels, Dual Phase Steels, Boron Steels and Aluminum Alloys. The process of trimming is the shearing off of extra material from a drawn panel. The process of flanging involves bending a portion of the blank, typically an end portion, at an angle with respect to the remainder of the blank. The process of hemming involves joining a plurality of panels, typically two panels, by positioning the panels adjacent one another and then folding an end portion of one panel over an end portion of the other panel.
Trimming dies usually incorporate a sharp upper trim steel, a sharp lower trim steel, and a clamping pad. Many high strength steels require large forces to be applied by trimming dies. Typically, to accomplish a good quality trimmed surface, the clearance between the shearing edges should be below 10% of the material thickness. High mechanical loads on the die may result in its insufficient stiffness, especially for high strength materials which can result in the opening of the clearance between the shearing edges during the trimming process. This can result in burrs on the stamped part. Additionally, use of conventional dies to trim high strength panels can result in rapid or excessive die wear and specifically increased wear of the trimming edges which need to be sharp. The embodiments disclosed herein addresses these and other problems.